341 lines
9.6 KiB
C
341 lines
9.6 KiB
C
/****************************************************************************
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* binfmt/libelf/libelf_symbols.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <inttypes.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/binfmt/elf.h>
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#include <nuttx/symtab.h>
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#include "libelf.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Constant Data
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: elf_symname
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*
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* Description:
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* Get the symbol name in loadinfo->iobuffer[].
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*
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* Returned Value:
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* 0 (OK) is returned on success and a negated errno is returned on
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* failure.
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*
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* EINVAL - There is something inconsistent in the symbol table (should
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* only happen if the file is corrupted).
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* ESRCH - Symbol has no name
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*
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****************************************************************************/
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static int elf_symname(FAR struct elf_loadinfo_s *loadinfo,
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FAR const Elf_Sym *sym)
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{
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off_t offset;
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size_t bytesread = 0;
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int ret;
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/* Get the file offset to the string that is the name of the symbol. The
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* st_name member holds an offset into the file's symbol string table.
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*/
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if (sym->st_name == 0)
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{
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bwarn("Symbol has no name\n");
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return -ESRCH;
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}
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/* Allocate an I/O buffer. This buffer is used by elf_symname() to
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* accumulate the variable length symbol name.
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*/
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ret = elf_allocbuffer(loadinfo);
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if (ret < 0)
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{
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berr("elf_allocbuffer failed: %d\n", ret);
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return ret;
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}
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offset = loadinfo->shdr[loadinfo->strtabidx].sh_offset + sym->st_name;
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/* Loop until we get the entire symbol name into memory */
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for (; ; )
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{
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FAR uint8_t *buffer = &loadinfo->iobuffer[bytesread];
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size_t readlen = loadinfo->buflen - bytesread;
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/* Get the number of bytes to read */
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if (offset + readlen > loadinfo->filelen)
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{
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if (loadinfo->filelen <= offset)
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{
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berr("At end of file\n");
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return -EINVAL;
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}
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readlen = loadinfo->filelen - offset;
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}
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/* Read that number of bytes into the array */
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ret = elf_read(loadinfo, buffer, readlen, offset + bytesread);
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if (ret < 0)
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{
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berr("elf_read failed: %d\n", ret);
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return ret;
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}
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bytesread += readlen;
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/* Did we read the NUL terminator? */
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if (memchr(buffer, '\0', readlen) != NULL)
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{
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/* Yes, the buffer contains a NUL terminator. */
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return OK;
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}
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/* No.. then we have to read more */
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ret = elf_reallocbuffer(loadinfo, CONFIG_ELF_BUFFERINCR);
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if (ret < 0)
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{
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berr("elf_reallocbuffer failed: %d\n", ret);
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return ret;
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}
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}
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/* We will not get here */
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return OK;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: elf_findsymtab
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*
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* Description:
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* Find the symbol table section.
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*
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* Returned Value:
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* 0 (OK) is returned on success and a negated errno is returned on
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* failure.
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*
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****************************************************************************/
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int elf_findsymtab(FAR struct elf_loadinfo_s *loadinfo)
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{
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int i;
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/* Find the symbol table section header and its associated string table */
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for (i = 1; i < loadinfo->ehdr.e_shnum; i++)
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{
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if (loadinfo->shdr[i].sh_type == SHT_SYMTAB)
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{
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loadinfo->symtabidx = i;
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loadinfo->strtabidx = loadinfo->shdr[i].sh_link;
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break;
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}
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}
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/* Verify that there is a symbol and string table */
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if (loadinfo->symtabidx == 0)
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{
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berr("No symbols in ELF file\n");
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return -EINVAL;
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}
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return OK;
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}
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/****************************************************************************
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* Name: elf_readsym
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*
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* Description:
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* Read the ELF symbol structure at the specified index into memory.
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*
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* Input Parameters:
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* loadinfo - Load state information
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* index - Symbol table index
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* sym - Location to return the table entry
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*
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* Returned Value:
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* 0 (OK) is returned on success and a negated errno is returned on
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* failure.
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*
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****************************************************************************/
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int elf_readsym(FAR struct elf_loadinfo_s *loadinfo, int index,
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FAR Elf_Sym *sym)
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{
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FAR Elf_Shdr *symtab = &loadinfo->shdr[loadinfo->symtabidx];
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off_t offset;
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/* Verify that the symbol table index lies within symbol table */
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if (index < 0 || index > (symtab->sh_size / sizeof(Elf_Sym)))
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{
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berr("Bad relocation symbol index: %d\n", index);
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return -EINVAL;
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}
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/* Get the file offset to the symbol table entry */
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offset = symtab->sh_offset + sizeof(Elf_Sym) * index;
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/* And, finally, read the symbol table entry into memory */
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return elf_read(loadinfo, (FAR uint8_t *)sym, sizeof(Elf_Sym), offset);
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}
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/****************************************************************************
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* Name: elf_symvalue
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*
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* Description:
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* Get the value of a symbol. The updated value of the symbol is returned
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* in the st_value field of the symbol table entry.
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*
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* Input Parameters:
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* loadinfo - Load state information
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* sym - Symbol table entry (value might be undefined)
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*
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* Returned Value:
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* 0 (OK) is returned on success and a negated errno is returned on
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* failure.
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*
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* EINVAL - There is something inconsistent in the symbol table (should
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* only happen if the file is corrupted).
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* ENOSYS - Symbol lies in common
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* ESRCH - Symbol has no name
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* ENOENT - Symbol undefined and not provided via a symbol table
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*
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****************************************************************************/
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int elf_symvalue(FAR struct elf_loadinfo_s *loadinfo, FAR Elf_Sym *sym,
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FAR const struct symtab_s *exports, int nexports)
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{
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FAR const struct symtab_s *symbol;
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uintptr_t secbase;
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int ret;
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switch (sym->st_shndx)
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{
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case SHN_COMMON:
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{
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/* NuttX ELF modules should be compiled with -fno-common. */
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berr("SHN_COMMON: Re-compile with -fno-common\n");
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return -ENOSYS;
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}
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case SHN_ABS:
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{
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/* st_value already holds the correct value */
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binfo("SHN_ABS: st_value=%08lx\n", (long)sym->st_value);
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return OK;
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}
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case SHN_UNDEF:
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{
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/* Get the name of the undefined symbol */
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ret = elf_symname(loadinfo, sym);
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if (ret < 0)
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{
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/* There are a few relocations for a few architectures that do
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* no depend upon a named symbol. We don't know if that is the
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* case here, but return and special error to the caller to
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* indicate the nameless symbol.
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*/
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bwarn("SHN_UNDEF: Failed to get symbol name: %d\n", ret);
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return ret;
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}
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/* Check if the base code exports a symbol of this name */
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symbol = symtab_findbyname(exports, (FAR char *)loadinfo->iobuffer,
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nexports);
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if (!symbol)
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{
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berr("SHN_UNDEF: Exported symbol \"%s\" not found\n",
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loadinfo->iobuffer);
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return -ENOENT;
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}
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/* Yes... add the exported symbol value to the ELF symbol table
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* entry
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*/
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binfo("SHN_UNDEF: name=%s "
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"%08" PRIxPTR "+%08" PRIxPTR "=%08" PRIxPTR "\n",
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loadinfo->iobuffer, (uintptr_t)sym->st_value,
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(uintptr_t)symbol->sym_value,
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(uintptr_t)(sym->st_value + (uintptr_t)symbol->sym_value));
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sym->st_value += (uintptr_t)symbol->sym_value;
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}
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break;
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default:
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{
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secbase = loadinfo->shdr[sym->st_shndx].sh_addr;
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binfo("Other: %08" PRIxPTR "+%08" PRIxPTR "=%08" PRIxPTR "\n",
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(uintptr_t)sym->st_value, secbase,
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(uintptr_t)(sym->st_value + secbase));
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sym->st_value += secbase;
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}
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break;
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}
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return OK;
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}
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